U.S. patent number 5,692,548 [Application Number 08/649,580] was granted by the patent office on 1997-12-02 for wood chipper.
This patent grant is currently assigned to Vermeer Manufacturing Company. Invention is credited to John Tibbe Breimer Bouwers, Thomas Alan Eggers.
United States Patent |
5,692,548 |
Bouwers , et al. |
December 2, 1997 |
Wood chipper
Abstract
A drum chipper for chipping wood material includes a chipping
drum having a blade mounted at an opening formed through a
circumferential surface of the drum. The drum includes an internal
conical surface positioned for a chip to flow radially inwardly
from the blade towards the conical surface and outwardly through an
axial face of the drum.
Inventors: |
Bouwers; John Tibbe Breimer
(Pella, IA), Eggers; Thomas Alan (Yankton, SD) |
Assignee: |
Vermeer Manufacturing Company
(Pella, IA)
|
Family
ID: |
24605419 |
Appl.
No.: |
08/649,580 |
Filed: |
May 17, 1996 |
Current U.S.
Class: |
144/174;
144/162.1; 144/172; 144/373; 241/101.74; 241/277; 241/278.1;
241/92 |
Current CPC
Class: |
B27L
11/002 (20130101); B27L 11/02 (20130101) |
Current International
Class: |
B27L
11/02 (20060101); B27L 11/00 (20060101); B27L
011/00 (); B02C 018/18 (); B02C 023/04 () |
Field of
Search: |
;144/162.1,172,173,174,373
;241/92,93,101.74,101.76,273.2,273.3,277,278.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bray; W. Donald
Attorney, Agent or Firm: Merchant, Gould, Smith, Edell,
Welter & Schmidt, P.A.
Claims
What is claimed is:
1. A chipper for chipping wood material, said chipper
comprising:
a frame having a material inlet and a chip outlet;
an engine;
a chipping member carried on said frame and including at least one
blade mounted in said frame for travel in a circumferential path of
travel about an axis of rotation;
said chipping member positioned for said blade to chip said
material at said inlet to form chips and with said chips projected
in a radial path generally radially inwardly from said blade toward
said axis;
said chipping member connected to said engine for said engine to
drive said chipping member for said blade to move in said path of
travel;
said chipping member further including a deflection surface
positioned for said chips to be deflected from said radial path to
an axial path;
said chip outlet positioned to receive said chips from said axial
path.
2. A chipper according to claim 1 wherein said chipping member
includes a plurality of said blades circumferentially spaced about
said axis of rotation.
3. A chipper according to claim 1 wherein said chipping member
comprises a drum having a circumferential surface and at least a
first axial face;
said circumferential surface including at least one opening formed
therein with said blade positioned at said opening to form said
chips at said opening with said chips passing through said opening
in said radial path.
4. A chipper according to claim 1 wherein said deflection surface
is set at an acute angle relative to said axis.
5. A chipper according to claim 3 wherein said deflection surface
is positioned radially inwardly of said circumferential surface and
at an angle relative to said axis for said deflection surface to
deflect said chips in said axial path through said axial face of
said drum.
6. A chipper according to claim 1 wherein said chipping member
further includes at least one discharge plate mounted for rotation
about said axis as said blade moves about said axis, said discharge
plate positioned to urge said chips from said axial path toward
said chip outlet.
7. A chipper according to claim 6 wherein said discharge plate
includes a portion thereof positioned radially away from said axis
a distance greater than a radial distance from said axis to said
blade.
8. A chipper according to claim 3 wherein said deflection surface
includes a generally conical surface disposed within said drum and
having a major diameter adjacent said axial face and a minor
diameter spaced from said face.
9. A chipper according to claim 4 wherein said angle is selected
for a shearing force acting to urge a chip at said deflection
surface into motion along said axial path to exceed a friction
force opposing said motion.
10. A chipper according to claim 8 including spaced walls defining
a pathway from said opening to said conical surface.
11. A chipper according to claim 3 wherein said drum includes a
plurality of discharge plates disposed at said axial face.
12. A chipper according to claim 1 wherein said drum includes first
and second halves each including a blade and a deflection surface
and an axial face wherein chips formed at said blade on said first
half are deflected by said deflection surface of said first half
through said axial face of said first half and wherein chips formed
at said blade on said second half are deflected by said deflection
surface of said second half through said axial face of said second
half;
said chip outlet positioned to receive chips from said axial faces
of both said first and second axial faces.
13. A chipper for chipping wood material including brush and logs,
said chipper comprising:
a frame having a material inlet and a chip outlet;
an engine;
a chipping member carried on said frame and including at least one
blade mounted in said frame for travel in a circumferential path of
travel about an axis of rotation;
said chipping member positioned for said blade to chip said
material at said inlet to form chips and with said chips projected
in a radial path generally radially inwardly from said blade toward
said axis and outwardly in a generally radial path;
said chipping member connected to said engine for said engine to
drive said chipping member for said blade to move in said path of
travel;
said chip outlet positioned to receive said chips from said axial
path;
at least one discharge plate mounted for rotation about said axis
as said blade moves about said axis, said discharge plate
positioned to urge said chips from said axial path toward said chip
outlet.
14. A chipper according to claim 13 wherein said discharge plate
includes a portion thereof positioned radially away from said axis
a distance greater than a radial distance from said axis to said
blade.
15. A chipper for chipping wood material including brush and logs,
said chipper comprising:
a frame having a material inlet and a chip outlet;
an engine;
a drum having a circumferential surface and at least a first axial
face;
said drum mounted for said circumferential face to oppose said
inlet and with said chip outlet at said axial face and with said
drum rotatable by said engine about an axis of said drum;
said circumferential surface including at least one opening formed
therein and having a blade positioned at said opening to form chips
at said opening with said chips passing through said opening in a
generally radial path;
means within said drum for directing said chips from said radial
path through said axial face.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention pertains to wood chippers and more particularly to
wood chippers having rotatable drums which carry blades on
circumferential walls of the drums.
2. Description of the Prior Art
Wood chippers are well known to reduce trees, limbs, branches,
bushes and the like to wood chips. Chippers come in a wide variety
of sizes and power ratings to handle wood material of varying
sizes.
In so-called "drum-type" chippers, the chipper includes a
cylindrical drum which carries knives or blades on the
circumferential wall of the drum. The drum is driven to rotate
about its cylindrical axis at high rotational velocities--for
example, 1050 revolutions per minute. Commonly, a drum is separated
into two halves with a plurality of knives positioned on both first
and second halves. For example, on each half, knives may be placed
at 180.degree. spacing. The knives in the first half are offset
from knives in the second half by 90.degree.. Therefore, four
different knives are provided on the drum to chip at a log being
fed towards the drum. Accordingly, the drum will make approximately
4,200 cuts per minute to produce numerous chips. The size of the
chip can be varied by varying the position of the blade on the
drum. An example of a drum chipper is shown in U.S. Pat. No.
5,005,620 to Morey dated Apr. 9, 1991.
An additional type of wood chipper is a so-called "disc-type"
chipper where cutting knives are carried radially on the face of a
spinning disc. An example of such a chipper is illustrated in U.S.
Pat. No. 3,861,602 dated Jan. 21, 1975 to Smith.
In both drum-type and disc-type chippers, the chipper will include
an inlet and an outlet. At the inlet, rollers or the like are
provided to feed a log toward the knives. The outlet typically
includes a discharge chute to receive chips and direct the chips in
a controlled direction so that the chips may be accumulated for
subsequent disposal.
In the design of chippers, it is desirable to avoid unnecessary
power consumption. With increased efficient design of chippers, the
feed rate of a log through a chipper can be increased to thereby
increase the production capabilities of a chipper.
We have found that prior art chippers restrict the maximum feed
rate of the chipper by reason of the unnatural path through which
the produced chips must pass. For example, with reference to the
aforementioned U.S. Pat. No. 5,005,620 (in particular, FIG. 7 of
that patent), chips are formed on the leading edge of a knife and
injected into a basket disposed beneath the knife. According to
that patent, the chips accumulated in the basket are then
discharged past a trailing edge of the knife. Even assuming this
method of operation, it will be noted that in order for the chips
to be discharged, the direction of the chips must be completely
changed. Specifically, the chips are first projected radially
inwardly into the drum and then ejected radially outward through
the drum. Accordingly, the momentum of the chip must be stopped and
reversed. Also, it is believed that chips do not necessarily follow
the path described in the aforementioned patent but may become
entrained within the basket thereby presenting an obstruction to
chips being formed and urged into the baskets. Also, we believe
that, in fact, in such a chipper, most chips continue to eject
radially outwardly from the forward edge of the knife with only a
small portion ejected past the trailing edge of the knife.
In drum chippers, the chipping action produces a large volume of
minute debris such as wood dust and the like. This debris may
accumulate within a chipping drum by reason of adherence of the
debris to itself and to the walls of the drum. Excessive
accumulation of such debris presents an obstruction to the free
flow of chips through the drum which may further reduce the feed
rate and productivity of the chipper.
It is an object of the present invention to provide a chipper in
which chips are directed through an unobstructive pathway such that
the chips do not interfere with one another and which avoids the
accumulation of debris within the drum.
II. SUMMARY OF THE INVENTION
According to a preferred embodiment of the present invention, a
chipper is provided having a frame with a material inlet and a chip
outlet. An engine is mounted to drive a chipper member. The chipper
member includes at least one blade mounted within the frame with
the blade movable about a circumferential path of travel about an
axis of rotation. The chipper member is positioned for the blade to
chip material provided at the inlet of the frame and to form chips,
at least some of which are projected in a generally radially inward
path from the blade toward the axis of rotation. The chipping
member further includes a deflection surface positioned for the
inwardly projected chips to be deflected from the radial path to an
axial path. The chip outlet is positioned to receive the chips from
the axial path.
With this novel structure, chips are not retained within the
chipping member such that the chips would otherwise interfere or
obstruct the travel of newly formed chips. Instead, a chip is
directed first radially inwardly into the chipping member and then
axially outwardly from the chipping member. This and other features
of the present invention to be more particularly described are
found to provide a chipper which can have an increased feed rate
and which reduces the accumulation of chipping debris within the
chipping member.
III. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a chipper according to the
present invention with side walls removed to expose interior
elements;
FIG. 2 is an end elevation view of a chipping drum (shown partially
in section) for use in the chipper of FIG. 1;
FIG. 3 is a perspective view of the drum of FIG. 2;
FIG. 4 is a side sectional view of the chipping drum of FIG. 2;
FIG. 5 is a top plan view of the chipping drum contained within a
frame with covering material partially removed to show interior
elements;
FIG. 6 is a diagrammatic representation of forces acting on a chip
impinging on an interior deflection surface of the drum of FIG.
2;
FIG. 7 is a side sectional view, shown in schematic form of an
alternative chipping drum with axially positioned discharge
plates;
FIG. 8 is a top sectional view of the drum of FIG. 7;
FIG. 9 is view similar to FIG. 7 showing an alternative
embodiment;
FIG. 10 is a top sectional view of the drum of FIG. 9;
FIG. 11 is a side sectional view of an embodiment of a chipping
drum;
FIG. 12 is a perspective view of an element of FIG. 11; and
FIG. 13 is a perspective view of the embodiment of FIG. 11.
IV. DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the several drawing figures in which identical
elements are numbered identically throughout, a description of the
preferred embodiment of the present invention will now be
provided.
With initial reference to FIG. 1, a chipper 10 is shown with side
walls removed to show interior elements. The chipper 10 includes a
frame 12 (mounted on wheels--not shown) having an inlet 14 and an
outlet 16. A novel chipping member in the form of a chipping drum
18 (as will be more fully described), is mounted within the frame
12 for rotation about an axis of rotation X--X. As is conventional,
the drum 18 is mounted such that logs or other material admitted
through inlet 14 are directed towards the drum 18 in a direction
generally radial to the axis X--X. Also, as is conventional,
rotating feed rollers (of which only one is shown at 20) are
provided which rotate about a generally vertical axis Y--Y to
receive logs or other material from the inlet 14. The feed rollers
20 are driven to direct and force the logs toward the rotating drum
18. An engine 22 is mounted on the frame 12 and coupled to the drum
18 by any suitable means to cause rotation of the drum about its
axis X--X. In the embodiment shown in FIG. 1, a belt 24 is
entrained around a drive pulley 26 mounted on an output of the
engine 22. The belt 24 is further entrained around a driven pulley
28 mounted on a shaft 30 coupled to the drum 18. It will be
appreciated that connections for driving drums and rotating drum
chippers are well known.
The present invention is principally directed to novel drum 18 and
attention is now directed to FIGS. 2-4. The drum 18 is generally
cylindrically and includes a circumferential surface 32 and a first
axial end 34 and a second axial end 34' Annular rings 35,35' are
provided at ends 34,34'.
The drum 18 includes a plurality of openings 38, 38' (see, FIG. 1)
formed through the circumferential surface 32. As shown in FIG. 4,
the drum includes a first half 18a and a second half 18b. The
halves 18a, 18b are substantially symmetrical and similar elements
are numbered identically with the elements on half 18b including
the designating apostrophe "'" to distinguish from the elements on
half 18a which are otherwise numbered identically.
On first half 18a, two openings 38 are provided on diametrically
opposed sides of the drum and offset by 180.degree. (see, FIG. 2).
Similarly, on drum half 18b, openings 38' are also provided
180.degree. separated with the openings 38' offset from openings 38
by 90.degree. relative to the axis of rotation X--X.
The drum 18 is hollow and contains two frustoconical surfaces
40,40'. For reasons that will be explained, the frusto-conical
surfaces 40,40' are disposed at an angle of about 30.degree.
relative to the axis of rotation X--X. Surfaces 40,40' may be
rolled steel to provide a smooth conical surface (FIG. 3) or may be
bent steel to provide a segmented conical surface comprised of a
plurality of flat surfaces (as illustrated in FIG. 1) or may be
formed through any other suitable means.
The frusto-conical surfaces 40,40' are provided with their axes
generally coaxial with the axis of rotation X--X. The
frusto-conical surfaces 40,40' are further positioned with their
major diameters at the annular rings 35,35' and with their minor
diameters joined at separating center plates 44,44' (see FIG. 4).
As shown in FIG. 4, the drum is supported by shaft 30 which has a
flange 31 bolted to the center plates 44,44'. Bearings 33,33'
support the shaft.
At each of the openings 38,38', blade mounting blocks 46,46' are
provided such that a cutting blade or knife 47,47' can be secured
to the blade mounting blocks 46,46'. As is typical, the blade
mounting blocks 46,46' permit the knife 47,47' to be adjusted in
its positioning on the blade mounting blocks 46,46' to permit the
formation of smaller or larger chips as might be desired by an
operator of the chipper 10. The use of such mounting blocks is not
necessary to practice the present invention.
Interior plates 50, 51, 50', 51' (best shown in FIG. 2) are
provided aligned with the openings 38,38'. The plates 50, 51, 50',
51' are generally parallel and spaced apart to define a pathway
52,52' from the openings 38,38' to the conical surfaces 40,40'.
Secured to the annular rings 35,35' are a plurality of discharge
plates 62,62'. The plates 62,62' extend axially away from the
mounting rings 35,35' with the plane of the plates 62,62' being
radial to the axis of rotation X--X. In order to provide structural
support for the plates 62,62', support gussets 64,64' are secured
to each of the plates at right angles to the plates 62,62'.
With the structure thus described, as the drum 18 is rotated in
direction A (FIG. 2), logs are fed by feed rollers 20 against the
circumferential surface 32. The blades 47,47' engage the logs to
cause chips to be cut off of the logs. The chips are forced through
the action of the drum 18 through the openings 38,38' and into the
pathways 52,52' defined between the plates 50, 51, 50',51'. The
chips are then directed into the interior of the drum defined by
the frusto-conical surfaces 40,40'. Within the interior of the
drum, the chips impinge upon the frustoconical surfaces 40,40'
which act as deflecting surfaces to deflect the chips outwardly
from the drum in an axial path of travel through the axial faces
34,34'. Accordingly, it will be noted that a chip first moves in a
general radially inward direction from the blades 37,37' to the
axis of rotation X--X and then axially outward through the axial
faces 34,34' of the drum 18.
With reference now to FIGS. 1 and 5, the frame 12 includes arcuate
sheathing 70 which substantially surrounds the circumferential
surface 32 of the drum 18 but which is open at an inlet 72 and an
outlet 74. Accordingly, the sheathing 70 does not interfere with
the advancement of logs from feed rollers 20 to the drum 18. With
reference to FIG. 5, at the axial faces 34,34', the sheathing 70
and side walls 76,76' cooperate to define discharge volumes 78,78'
adjacent both axial faces 34,34' of the drum 18. The discharge
volumes 78,78' are in particle flow communication with the entrance
portion 82 of discharge chute 16. Therefore, as chips are axially
expelled from the rotating drum 18, the discharge plates 62 force
the expelled chips into the entrance portion 82 and out of the
discharge chute 16.
As previously mentioned, the surface of the conical surfaces 40,40'
are set an angle of about 30.degree. to the axis X--X of rotation
of the drum 18. More specifically, the angle of the conical
surfaces are set to ensure that material on the conical surfaces
40,40' do not adhere to the conical surfaces 40,40' but instead is
directed outwardly through the axial faces 34,34' of the drum
18.
FIG. 6 illustrates what is presently believed to be the physics of
the interaction of chips on a conical surface 40. In FIG. 6, a
portion of the conical surface 40 is shown relative to the axis
X--X of rotation. Vector F illustrates the force at which a chip
impinges upon the conical surface 40. This vector F includes both a
normal component F.sub.n which is perpendicular to the surface 40
and a resultant shear component F.sub.s. The shear vector F.sub.s
represents the force acting on the chip causing it to move in a
direction generally parallel to the wall of the conical surface 40
(i.e., in a desired path of travel which is axially out of the drum
18). Opposing the axial movement of the chip is a frictional force
F.sub.f. The frictional force is equal to the product of the normal
force F.sub.n times the coefficient of friction of wood chips on
the steel surface of the cone 40. In order to prevent adherence and
accumulation of wood debris on the cone 40, the shear vector
F.sub.s must be greater than the friction vector F.sub.f. Through
Applicant's calculations, if the angle B between the cone 40 and
the axis X--X is about 30.degree., the shear force F.sub.s is about
two or three times the frictional force F.sub.f.
With the construction thus described, a chip is projected radially
inwardly to the rotating drum 18. A chip may either bounce off of
the cones 40,40' and be directed through the axial faces 34,34' of
the drum or the chip may slide off of the wall of the cones 40,40'
since the angle of the cones 40,40' relative to the axis X--X is
selected for the shear force at the surface to be greater than the
frictional force opposing the desired sliding motion. In tests,
Applicants have noted that not all chips are projected radially
inwardly. Instead, most formed chips are immediately ejected
radially outwardly from the knives 47,47' at the leading edge of
the knives. However, the presence of the pathways 52,52' to the
conical surfaces 40,40' provides an alternative path for chips
which would not otherwise exit radially and which would otherwise
interfere with new chip formation. The result of the alternate
pathway is a drum chipper having a much improved material feed
rate.
As previously discussed, chips are removed from the axial faces
34,34' of the drum 18 by reason of the rotating discharge plates
62,62'. FIGS. 9-10 illustrate an alternative design in a drum 18'
where discharge plates 62a, 62a' are provided with their radial
tips 63,63' spaced from the axis of rotation X--X a distance
greater than the diameter of the drum 18' With this modified
design, the tip speed of the discharge plates 62a, 62a' is
increased. Therefore, greater kinetic energy is applied to the
chips. As a result of the larger discharge plates 62a,62a', for any
given drum speed, increased force is provided to remove the chips
from the drum. Therefore, a drum can be slowed to increase the
torque of the drum shaft and make the chipper quieter. Also, in
FIGS. 9-10, the drum 18' is shown with a modified design where
axial direction of a chip from blades 47a is achieved by providing
solid drum 18' with a cut-out pocket 100 at the blades 47a in
communication with side chambers 78a,78a' defined between frame
sidewalls 76a,76a' and drum axial faces 34a,34a'. This defines a
chip pathway 101 which has a radially inward portion and an axial
outward portion. Also, circumferential frame 70' is V-shaped to
define a clearance for enlarged plates 62a,62a' and to direct
radially expelled chips to the plates 62a,62a'.
The use of discharge plates 62 on the axial ends 34,34' of the drum
18 have been illustrated in the preferred embodiment with respect
to novel drum 18. However, such plates could also be used with
respect to drums such as that shown in U.S. Pat. No. 5,005,620 by
simply providing a side path for chips to be directed from the
cutting knives of the chipper to the paddles. FIGS. 7 and 8
illustrate such an embodiment where a pocket is formed behind the
plates in a solid drum. In FIGS. 7 and 8, the drum 18" is similar
to drum 18' in FIG. 9-10 except the discharge plates 62b in drum
18" are smaller than plates 62a in FIGS. 9-10. Plates 62b have a
radially outer tip 63" spaced from axis X--X equal to the diameter
of drum 18". In either of the embodiments of FIGS. 7-10, the chip
path need not extend into the drum and then axially outward.
Instead, a chip can be projected radially outward and then directed
to the discharge plates 62a,62b by the shielding 70' to take
advantage of the invention of the plates 62a,62b.
By reason of the foregoing structure, Applicants have achieved the
obviousness of the invention in the form of an improved chipper
with an improved feed rate. Further, accumulation of debris within
the chipper drum is minimized.
Having disclosed the present invention in a preferred embodiment,
it has been shown how the objects of the invention have been
attained. However, modifications and equivalents of the disclosed
concepts such as those which readily occur to one skilled in the
art are intended to be included within the scope of the claims
which are appended hereto.
* * * * *